Hello!
> You aren't opening it with O_NDELAY by any chance?
Hopefully not :) Even plain cat exhibits the problem.
> Please look with strace.
| albireo:/home/mj# strace cat /dev/usb/lp0
| execve("/bin/cat", ["cat", "/dev/usb/lp0"], [/* 34 vars */]) = 0
| uname({sys="Linux", node="albireo", ...}) = 0
| brk(0) = 0x804d000
| access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or
directory)
| mmap2(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0xb7fbb000
| access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or
directory)
| open("/etc/ld.so.cache", O_RDONLY) = 3
| fstat64(3, {st_mode=S_IFREG|0644, st_size=97571, ...}) = 0
| mmap2(NULL, 97571, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb7fa3000
| close(3) = 0
| access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or
directory)
| open("/lib/tls/libc.so.6", O_RDONLY) = 3
| read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\240O\1"..., 512) =
512
| fstat64(3, {st_mode=S_IFREG|0644, st_size=1245488, ...}) = 0
| mmap2(NULL, 1251484, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) =
0xb7e71000
| mmap2(0xb7f99000, 28672, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x128) = 0xb7f99000
| mmap2(0xb7fa0000, 10396, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xb7fa0000
| close(3) = 0
| mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0xb7e70000
| mprotect(0xb7f99000, 20480, PROT_READ) = 0
| set_thread_area({entry_number:-1 -> 6, base_addr:0xb7e708e0, limit:1048575,
seg_32bit:1, contents:0, read_exec_only:0, limit_in_pages:1, seg_not_present:0,
useable:1}) = 0
| munmap(0xb7fa3000, 97571) = 0
| brk(0) = 0x804d000
| brk(0x806e000) = 0x806e000
| open("/usr/lib/locale/locale-archive", O_RDONLY|O_LARGEFILE) = 3
| fstat64(3, {st_mode=S_IFREG|0644, st_size=1673120, ...}) = 0
| mmap2(NULL, 1673120, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb7cd7000
| close(3) = 0
| fstat64(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 4), ...}) = 0
| open("/dev/usb/lp0", O_RDONLY|O_LARGEFILE) = 3
| fstat64(3, {st_mode=S_IFCHR|0660, st_rdev=makedev(180, 0), ...}) = 0
| read(3, "", 4096) = 0
| close(3) = 0
| close(1) = 0
| exit_group(0) = ?
| Process 4888 detached
> If that looks ok, a usbmon trace would be helpful.
> Please send me both traces.
albireo:/sys/kernel/debug/usbmon# cat 1u
# (ran cat for the first time)
ddbeb7c0 1940101507 S Bi:1:003:1 -115 1024 <
ddbeb7c0 1940101645 C Bi:1:003:1 0 0
ddbeb7c0 1940101675 S Bi:1:003:1 -115 1024 <
ddbeb7c0 1940101766 C Bi:1:003:1 -2 0
# (2nd time)
ddbebec0 1943391766 S Bi:1:003:1 -115 1024 <
ddbebec0 1943391838 C Bi:1:003:1 0 0
ddbebec0 1943391881 S Bi:1:003:1 -115 1024 <
ddbebec0 1943391959 C Bi:1:003:1 -2 0
Have a nice fortnight
--
Martin `MJ' Mares <[EMAIL PROTECTED]>
http://mj.ucw.cz/
Faculty of Math and Physics, Charles University, Prague, Czech Rep., Earth
Maintenance-free: When it breaks, it can't be fixed...
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